Organic solvents are used in the manufacturing process of conventional composite films. Although the organic solvents are recyclable, the setup cost of recycling equipment is very high, and it is quite difficult to reach a recovery rate of 100%. Thus, it is difficult to achieve zero detection of the organic solvents, which does not meet the requirements of environmental protection. In addition, the manufacturing process of conventional composite films is complicated, which easily leads to energy consumption. Moreover, the adhesion strength of the composite films made by the conventional manufacturing process is generally poor.
The conventional composite film and manufacturing method thereof are analyzed in the following patent documents in the prior art.
1. TW Patent Applicant No. 087109330
Approach: “uncured rubber base material” and “semi-finished EVA shoes” are laminated by using toluene and a cleaning agent, and then they are laid aside, heated, ripened and cooled.
Disadvantage: organic solvents that harm the earth environment are used in the method, and the production process is complicated and long, and is uneconomic.
2. TW Patent Applicant No. 087117457
Approach: an adhesive is used to bond soles and heels.
Disadvantage: the adhesive contains organic solvents, which may affect the environment.
3. TW Patent Applicant No. 094111508
Approach: a cross-linking agent remaining on an upper layer of a rubber decorative piece and an outsole blank (EVA foamed material) are bonded for formation through a cross-linking reaction.
Disadvantage: the cross-linking agent belongs to organic solvents, and may harm the environment.
4. TW Patent Applicant No. 101215489
Approach: in a fixing structure of steel-toed shoes, shoe uppers and outsoles are fixed to each other through riveting with inverted-U-shaped nails.
Disadvantage: no other manners are provided to enhance fixing of the metal. As inner sides of the steel-toed shoes only had metal and are not protected by other materials, resulting in that socks quickly wore out and cause a toe injure and so on.
5. TW Patent Applicant No. 099104504
Approach: a TPR (thermoplastic rubber membrane) of 400 to 500 microns is laminated to a metal sheet, and in a flat plate or roller pressing and heating manner, leather formed by natural fibers, man-made fibers, blend spinning and dermis is laminated on the other side of the sheet.
Disadvantage: the TPR cannot be laminated to the EVA foamed material, and moreover the process required heating by an oven, the procedure is long, and too much energy was consumed.
6. TW Patent Applicant No. 102110171
Approach: the invention provides a hot melt adhesive highly favorable to environmental protection, which has sufficient pressure-sensitive adhesion, adhesive force and thermal stability.
Disadvantage: the peeling strength is less than 1 kgf/cm, a film shape is not formed, and no particular production method is provided.
Based on the foregoing analysis, it is necessary to provide a high adhesion composite film and manufacturing method thereof, so as to solve the foregoing deficiencies in the prior art.